DNA Fingerprint Lab Flashcards
Restriction Endonucleases aka
restriction enzymes
What do restriction enzymes do
They cut lengths of DNA at specific sequences of 5 or 20 bases called restriction sites.
Each enzyme recognizes its own restriction site sequence: DNA from any individual contains restriction sites for every restriction enzyme. there are hundreds of thousands of sites for each enzyme which are scattered at random throughout gnomic DNA.
What are silent DNA
Dna that does not code for anything
2 importnat factors about silent DNA in reference to restriction sites
1 It contains a lot of restriction sites for many restriction enzymes.
2. it tends to mutate easily and to slowly accumulate tandem repeats
TANDEM REPEATS
Area of DNA where a specific sequence of bases is duplicated many times
Why are Tandem repeats used as “fingerprint” for an individual
Although the number of times a tandem repeat sequece is repeated in a specific area of DNA is highly variable, they will be the same in every cell of one individual.
The PATTERN of all tandem repeat locations in silent DNA is unique and can be used as a “ fingerprint” for that individual.
How are the tandem repeats measured
by measuring the the restriction fragment containing it.
Longer tandem repeats = longer restriction fragments
RESTRICTION FRAGMENTS
A piece of DNA produced when an area of silent DNA containing tandem repeats is cut in 2 places by the same restriction enzyme.
FINGERPRINT REGIONS
Designated certain silent DNA regions of human genome that are universal standard “ fingerprint regions”.
These areas have known restriction sites with known locations for tandem repeats between them.
how are RESTRICTION FRAGMENTS ( the real DNA fragments) produced
The human DNA is cut with a battery of restriction enzymes that cut in the fingerprint regions and then measure the length of the restriction fragments generated. the lengths of the different fragments are the real” “ DNA fragment”
Why are we recombinants in terms of the tandem repeats we inherit
- the length of the restriction fragments in an individual will not change and therefore will appear unchanged in the gametes of that individual.
- the areas of tandem repeats are similar to gene alleles in that they can be passed intact to their offsprings.
POLYMORPHISM
a gene that exists in multiple forms ( eg. ABO blood type)
RESTRICTION FRAGMENT LENGTH POLYMORPHISMS
are differences in restriction fragment lengths 9 due to tandem repeats0 at a particular location in DNA
How is DNA fingerprint determined
measure the length of the RFLPS generated when a subject’s DNA is cut with a battery of standard restriction enzymes
How is DNA size expressed
in terms of based pairs (bp)
